Using starquakes to determine the interior structure of stars ... and the age of the milky way galaxy.
You've heard of earthquakes caused by the movement of material inside our planet. Well, stars do the same kind of thing. "The quakes generate soundwaves inside the stars that make them ring, or vibrate," and this trembling causes a tiny but measurable variation in the star's brightness. And the way this ringing occurs is dependent on the internal structure of the star, which is itself dependent on its age. This branch of astronomy is known as asteroseismology
Using data from the orbiting now-defunct Kepler telescope - which, astonishingly, was so sensitive it could measure the brightness dip caused by a flea walking across a car headlight - a team of astronomers has determined the age of a particular population of stars in our galaxy's disc, so solving a long standing contradiction about the age of different parts of our galaxy. The Milky Way galaxy is about 10 billion years old.
[Spiral Galaxy NGC 6744] Beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo and appears as only a faint, extended object in small telescopes.
We see the disk of this nearby island universe tilted towards our line of sight in this remarkably detailed galaxy portrait, a telescopic view that spans an area about the angular size of a full moon. In it, the giant galaxy's elongated yellowish core is dominated by the light from old, cool stars. Beyond the core, grand spiral arms are filled with young blue star clusters and speckled with pinkish star forming regions. An extended arm sweeps past a smaller satellite galaxy (NGC 6744A) at the lower right. NGC 6744's galactic companion is reminiscent of the Milky Way's satellite galaxy the Large Magellanic Cloud.
Hubble team breaks cosmic distance record. By pushing NASA’s Hubble Space Telescope to its limits, an international team of astronomers has shattered the cosmic distance record by measuring the farthest galaxy ever seen in the universe. This surprisingly bright infant galaxy, named GN-z11, is seen as it was 13.4 billion years in the past, just 400 million years after the Big Bang. GN-z11 is located in the direction of the constellation of Ursa Major. “We’ve taken a major step back in time, beyond what we’d ever expected to be able to do with Hubble. We see GN-z11 at a time when the universe was only three percent of its current age,” explained principal investigator Pascal Oesch of Yale University.
Coincidentally, these objects are very close in the sky to where the interstellar comet 2I/Borisov came from. These nebulae are about 6,000 and 6,500 light years away in a different spiral arm of the Milky Way to us, though, and the comet must surely be a much more local object.
Established theory comes head-to-head with new observational evidence ... and doesn't survive the experience!
Pulsars are rapidly rotating collapsed stars that beam energy from both north and south poles like searchlights. The physics of these extreme objects is well established and it was known from this that a pulsar would have a hot spot at each pole and a fairly even, if very high, lower temperature elsewhere.
It is only very recently, though, that actual observational evidence has come available for what the surface of any pulsar actually looks like. And it looks completely different from what was expected.
Pulsar J0030 has been observed with the NICER X-ray telescope on board the International Space Station, and while 2 [or maybe 3] hotspots are seen they are not at the poles at all, and are all in one hemisphere.
Clever boffins have come up with new, and much more complex, theories to explain the observations.
I recently heard NDT mention that it is predicted that since the universe is expanding at an accelerating rate, there will come a time when it will be impossible for us to glimpse or study in any way any galaxy other than our own, because other galaxies will be just too far away.
But, yes, quite true - assuming current interpretations of supernova observations are correct, then the universe is now expanding at an accelerating rate due to to reasons unknown and inexplicable, and given the name of Dark Energy to try and kid ourselves that we have the faintest idea of what the reasons are behind this.
As I see it, a few billion years ago, for reasons unknown, the expansion of the universe started accelerating. Who's to say that at some time in the future the brakes won't be applied?
What with dark energy and dark matter, about 95% of everything is not understood at all. A bit humbling really. So making any predictions about the cosmological future is audacious to say the least!